Numerous small gram-negative bacilli infect and cause serious disease in animals. Vaccines against these pathogens are normally either killed or attenuated whole cell bacterins. While there are many reports in the literature on studies of the antigenic components of these bacteria, there is little reported respecting commercially viable processes for making acellular (cell-free) or subunit vaccines for these pathogens.
Vedros, N.A., and Giard, R. (Abstract presented at the 13th Annual Conference and Workshop and 7th Eastern Fish Health Workshop, May 1982) disclosed a process for preparing a crude acellular vaccine for Pasteurella multocida infections in marine mammals. A culture of the organisms was shaken with glass beads and then centrifuged. The culture supernatant wa treated with ammonium sulfate and the resulting precipitate was alkaline digested and gel filtered to remove low molecular weight materials. The resulting vaccine consisted mainly of surface or capsular polysaccharide with minor amounts of protein and nucleic acids. While the process provided an effective vaccine, it was too complex and costly to provide a commercially viable way to prepare veterinary vaccines on a large scale.
Monogr. Allergy (1975) 9:245-258 describes a process for making a polysaccharide vaccine for preventing meningococcal disease in humans. A culture of Neisseria meningitidis was treated with 1% Cetavlon to kill the meningococci and precipitate polysaccharides from solution. The precipitate and bacterial debris were collected by centrifugation and then treated with a calcium chloride solution to dissociate polysaccharide-Cetavlon complexes. Nucleic acids were then precipitated with ethanol and removed. Polysaccharides were precipitated with additional ethanol and washed with ethanol and acetone to remove residual salt and Cetavlon and yield a 50% pure product. Further purification of the polysaccharide was achieved by chloroform-butanol extraction followed by ultracentrifugation or by phenol extraction followed by dialysis and sedimentation. This procedure for making a human vaccine is also too costly and complex to be adapted for producing veterinary vaccines in commercial quantities.